SUMMARY The solution, absorptive, and adsorptive properties of nitroglycerin are related to problems encountered in the intravenous use of solutions of the drug and in its assay in biological tissues. Solutions of the drug in usual intravenous fluids are quite stable to hydrolysis under neutral conditions. Loss to plastic intravenous delivery set components by rapid adsorption and slower absorption processes present a significant clinical problem. Assay of the drug and its major metabolites is complicated by problems of extraction related to the solubility of nitroglycerin, its metabolites and substances in the plasma. Loss of nitroglycerin incubated with red blood cells is a very rapid process (half‐life 4·0 min. at 10 ng/ml). The mechanism appears to be a physical process rather than an enzymatic one. The loss to blood cells and perhaps other biological materials should be considered in an analysis of the distribution of the drug.

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Background Pre-sleep protein has been shown to improve muscle recovery overnight following exercise-induced muscle damage. Whether such an approach affects recovery from sprint interval training (SIT) has yet to be elucidated. This study examined the effects of protein supplementation every night before sleep on early (45 min post-SIT) and late (24 and 48 h after SIT) responses of creatine kinase (CK) and inflammatory cytokines, including interleukin-6 and 10 (IL-6 and IL-10) and tumor necrosis factor-alpha (TNFα). Methods Twenty trained swimmers underwent a 2-week in-water swimming SIT (two sets of 12 × 50-m all-out swims, interspersed by 1:1 recovery between each sprint and 3 min of rest between sets) and were randomized to two intervention groups receiving either 0.5 g kg −1 day −1 protein beverage (PRO) or the same amount of carbohydrate (CHO) preceding going to bed every night. For initial and final training sessions, CK and cytokine responses were analyzed at different time points, including resting, immediately after completion, 45 min post-SIT, and 24 and 48 h after SIT. Results CK concentrations elevated from resting point to 24 and 48 h post-SIT for both PRO and CHO groups ( p < 0.05). In both training groups, the peak levels of IL-6 and 10 were observed 45 min post-SIT on both occasions. TNFα levels significantly elevated from rest to immediately after SIT ( p < 0.001) and returned to values equivalent to the baseline afterward in both groups and on both occasions. In both groups, swimming SIT also switched the cytokine response 48 hours after exercise to an anti-inflammatory status by decreasing the ratio of IL-6 to IL-10 ( p < 0.04) in the last training session. Conclusions Pre-sleep protein ingestion failed to ameliorate blood markers of muscle damage. The late anti-inflammatory profile of cytokines and exercise-induced muscle damage improved after two weeks of swimming SIT with either protein or carbohydrate ingestion before sleep.